4

他の同様の質問を見てきましたが、私がやろうとしていることとは少し違うようです。

2 つのカウント値を選択している単一のクエリがあり、一方を他方で除算したいと考えています。

ここに私の作業コードがあります:

SELECT (SELECT count(DISTINCT s.lastfirst) 
          FROM students s
          JOIN cc ON s.id = cc.studentid
          JOIN courses c on cc.course_number = c.course_number
         WHERE cc.schoolid='109'
           AND c.course_name LIKE 'AP %' 
           AND substr(cc.termid,0,1) <> '-'
           AND cc.dateenrolled BETWEEN to_date('08/01/2010','MM/DD/YYYY') AND  
               to_date('08/01/2011','MM/DD/YYYY')) as AP, 
       (SELECT count(DISTINCT s.lastfirst) 
          FROM students s
          JOIN cc ON s.id = cc.studentid
          JOIN courses c on cc.course_number = c.course_number
         WHERE cc.schoolid = '109'
           AND substr(cc.termid,0,1) <> '-'
           AND cc.dateenrolled BETWEEN to_date('08/01/2010','MM/DD/YYYY') 
           AND to_date('08/01/2011','MM/DD/YYYY')) as ttl
 FROM DUAL

ここで私はそれを壊します：

SELECT (SELECT count(DISTINCT s.lastfirst) 
          FROM students s
          JOIN cc ON s.id = cc.studentid
          JOIN courses c on cc.course_number = c.course_number
         WHERE cc.schoolid='109'
           AND c.course_name LIKE 'AP %' 
           AND substr(cc.termid,0,1) <> '-'
           AND cc.dateenrolled BETWEEN to_date('08/01/2010','MM/DD/YYYY') 
           AND to_date('08/01/2011','MM/DD/YYYY')) as AP, 
       (SELECT count(DISTINCT s.lastfirst) 
          FROM students s
          JOIN cc ON s.id = cc.studentid
          JOIN courses c on cc.course_number = c.course_number
         WHERE cc.schoolid = '109'
           AND substr(cc.termid,0,1) <> '-'
           AND cc.dateenrolled BETWEEN to_date('08/01/2010','MM/DD/YYYY')
           AND to_date('08/01/2011','MM/DD/YYYY')) as ttl,
      (AP / ttl) as pcnt
 FROM DUAL

誰かがこれを行う適切な方法を教えてください。

ありがとうございました

4

1 に答える 1

7

最も簡単な答えは、2 つの値を除算することです。

SELECT (SELECT count(DISTINCT s.lastfirst) 

FROM students s
JOIN cc ON s.id = cc.studentid
JOIN courses c on cc.course_number = c.course_number    
WHERE cc.schoolid='109'    
AND c.course_name LIKE 'AP %'     
AND substr(cc.termid,0,1) <> '-'    
AND cc.dateenrolled BETWEEN to_date('08/01/2010','MM/DD/YYYY') 
    AND to_date('08/01/2011','MM/DD/YYYY')) /    
(SELECT count(DISTINCT s.lastfirst)     
FROM students s
JOIN cc ON s.id = cc.studentid
JOIN courses c on cc.course_number = c.course_number       
WHERE cc.schoolid = '109'    
AND substr(cc.termid,0,1) <> '-'    
AND cc.dateenrolled BETWEEN to_date('08/01/2010','MM/DD/YYYY') 
    AND to_date('08/01/2011','MM/DD/YYYY')) as quotient

FROM DUAL

値を保持して商を得たい場合は、次のようにします。

SELECT AP, ttl, AP/ttl AS quotient
FROM (
SELECT (SELECT count(DISTINCT s.lastfirst) 
          FROM students s
          JOIN cc ON s.id = cc.studentid
          JOIN courses c on cc.course_number = c.course_number
         WHERE cc.schoolid='109'
           AND c.course_name LIKE 'AP %' 
           AND substr(cc.termid,0,1) <> '-'
           AND cc.dateenrolled BETWEEN to_date('08/01/2010','MM/DD/YYYY') AND  
               to_date('08/01/2011','MM/DD/YYYY')) as AP, 
       (SELECT count(DISTINCT s.lastfirst) 
          FROM students s
          JOIN cc ON s.id = cc.studentid
          JOIN courses c on cc.course_number = c.course_number
         WHERE cc.schoolid = '109'
           AND substr(cc.termid,0,1) <> '-'
           AND cc.dateenrolled BETWEEN to_date('08/01/2010','MM/DD/YYYY') 
           AND to_date('08/01/2011','MM/DD/YYYY')) as ttl
 FROM DUAL)

ただし、この時点では、SQL ではなく呼び出しコードで除算を行うこともできます。これは、いずれにしても 2 つのスカラー値を持つ 1 つの結果行を選択しているだけだからです。

于 2012-11-05T17:27:02.793 に答える